Engine Timing Marks - Piper ARROW III Service Manual

2. Turn rotating magnet in direction of rotation until painted chamfered tooth of distributor gear is
just becoming visible in timing window. Continue turning rotating magnet until line on end of cam
is aligned with mark at top of breaker housing. (Refer to Figure 8-15.) Tighten adjusting knob of
the holding tool to hold rotating magnet.
3. Fabricate a pointer as shown in Figure 8-16 and install the pointer under the cam screw so the
pointer indexes in the center of "E" gap position.
4. Connect the 11 -9110 Timing Light or equivalent across breaker assembly. Adjust breaker contacts
to just open at this position.
5. Loosen holding tool and turn rotating magnet until cam follower is on high point of cam lobe.
Tighten holding tool and measure contact clearance. It must be 0.018 ± 0.006. If necessary,
readjust breaker. Check to be sure contacts open within "E" gap tolerance. Replace breaker
assembly if "E" gap tolerance and contact clearance cannot be obtained. Tighten breaker screws to
20 to 25 inch-pounds and recheck breaker settings.
8-39. MAGNETO INSTA L L ATION AND TIMING PROCEDURE (MAGNETO TO ENGINE). (Refer to
Figure 8-17.)
a. The timing marks are on the outer edge of the crankshaft counterweight blade between No. 2 and No.
4 cylinders. The inspection plug between No. 2 and No. 4 cylinders on the left top side of the
crankcase must be removed to view the marks on the crankshaft.
1. Plug one spark plug hole of the No. 1 cylinder and place a thumb over the other plug hole. Have a
second person stand in front of the engine and turn the crankshaft in a counterclockwise direction
until pressure is felt on the thumb. No. 1 piston is coming up on the compression stroke.
2. Remove the inspection hole plug and turn the crankshaft counterclockwise until the 20 degree
BTC mark appears in the center of the inspection hole. A timing device as described in Service
Bulletin M68-2, Rev. 1 may also be used.
Revised: 8/31/77
CHEROKEE ARROW III SERVICE MANUAL
Figure 8- 17. Engine Timing Marks
2B13
POWER PLANT - CONTINENTAL